docs: def send_message_sync(
          self,
          message: Message,
          sender: str = None,
          recipients: RecipientsType = None,
          mail_options: Iterable[str] = None,
          rcpt_options: Iterable[str] = None,
          timeout: DefaultNumType = _default,
      ) -> SendmailResponseType:
          """
          Synchronous version of :meth:`.send_message`. This method
          starts the event loop to connect, send the message, and disconnect.
          """
          return self._run_sync(
              self.send_message,
              message,
              sender=sender,
              recipients=recipients,
              mail_options=mail_options,
              rcpt_options=rcpt_options,
              timeout=timeout,
          )